首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1415206篇
  免费   114085篇
  国内免费   3351篇
耳鼻咽喉   18431篇
儿科学   46669篇
妇产科学   41199篇
基础医学   201429篇
口腔科学   38240篇
临床医学   126416篇
内科学   285310篇
皮肤病学   33447篇
神经病学   117280篇
特种医学   53912篇
外国民族医学   464篇
外科学   210993篇
综合类   32784篇
现状与发展   3篇
一般理论   487篇
预防医学   110477篇
眼科学   31546篇
药学   98753篇
  1篇
中国医学   3381篇
肿瘤学   81420篇
  2021年   11022篇
  2019年   11856篇
  2018年   16777篇
  2017年   12802篇
  2016年   14416篇
  2015年   16198篇
  2014年   22788篇
  2013年   33669篇
  2012年   45802篇
  2011年   48336篇
  2010年   28371篇
  2009年   27212篇
  2008年   44558篇
  2007年   47098篇
  2006年   47621篇
  2005年   46062篇
  2004年   43948篇
  2003年   41878篇
  2002年   40321篇
  2001年   73082篇
  2000年   74590篇
  1999年   61628篇
  1998年   17018篇
  1997年   15447篇
  1996年   15593篇
  1995年   14809篇
  1994年   13405篇
  1993年   12591篇
  1992年   45862篇
  1991年   43510篇
  1990年   41510篇
  1989年   39567篇
  1988年   36195篇
  1987年   35362篇
  1986年   32867篇
  1985年   31288篇
  1984年   23834篇
  1983年   20027篇
  1982年   12213篇
  1981年   10784篇
  1979年   20715篇
  1978年   14583篇
  1977年   12087篇
  1976年   11370篇
  1975年   11623篇
  1974年   13998篇
  1973年   13543篇
  1972年   12638篇
  1971年   11477篇
  1970年   10916篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
82.
At this study a multi-criteria model was developed to examine the available procedures, techniques and methods of handling infectious waste in the large healthcare unit of University Regional General Hospital of Patras, Western Greece. Particularly, this study examined the: a) current legislation and Directives issued for medical waste management at Greece and among the other EU-members, b) contribution of healthcare wastes (HCW) generation rate on social and economic parameters in selected European countries, c) available procedures, techniques, and methods upon the disposal of infectious wastes at the healthcare studied, and, d) propositions for integrated management of such hazardous wastes. Specifically, the Analytic Hierarchy Process (AHP) methodology was applied under pair wise comparison matrices in two stages: 1) the scale factors and the indicators, and 2) the criteria and their sub–criteria. The assessment of these pair wise matrices included the indicators and the sub–criteria. Subsequently, two pair wise comparison matrices, upon a) the “Fulfillment of environmental objectives” indicator and b) the “Energy consumption” sub criterion, were denoted. The AHP methodology yielded good results; however there is still space of improving the environmental performance. The normalized relative weights obtained for the criteria and sub criteria motivated specific actions that have to be handled. Particularly, the results indicated a very good value in environmental management criteria due the values obtained for the commitment towards the environmental policy standards and the waste management procedures. However, further improvements on staff awareness (such as development programs to enhance sensitivity) and more green purchasing suppliers, should be further addressed.  相似文献   
83.
84.
85.
First described in 1955 in New Jersey, epizootic haemorrhagic disease (EHD) causes a severe clinical disease in wild and domestic ruminants worldwide. Epizootic haemorrhagic disease outbreaks occur in deer populations each year from summer to late autumn. The etiological agent is EHD virus (EHDV) which is a double‐stranded segmented icosahedral RNA virus. EHD virus utilizes point mutations and reassortment strategies to maintain viral fitness during infection. In 2018, EHDV serotype 2 was predominantly detected in deer in Illinois. Whole genome sequencing was conducted for two 2018 EHDV2 isolates (IL41747 and IL42218) and the sequence analyses indicated that IL42218 was a reassortant between different serotypes whereas IL41747 was a genetically stable strain. Our data suggest that multiple strains contribute to outbreaks each year.  相似文献   
86.
87.
88.

Background Context

Low back pain (LBP) is a common complaint in clinical practice of multifactorial origin. Although obesity has been thought to contribute to LBP primarily by altering the distribution of mechanical loads on the spine, the additional contribution of obesity-related conditions such as diabetes mellitus (DM) to LBP has not been thoroughly examined.

Purpose

To determine if there is a relationship between DM and LBP that is independent of body mass index (BMI) in a large cohort of adult survey participants.

Study Design

Retrospective analysis of prospectively collected National Health and Nutrition Examination Survey (NHANES) data to characterize associations between LBP, DM, and BMI in adults subdivided into 6 subpopulations: normal weight (BMI 18.5–25), overweight (BMI 25–30), and obese (BMI >30) diabetics and nondiabetics. Diabetes was defined with glycohemoglobin A1c (HbA1c) 6.5%.

Patient Sample

11,756 participants from NHANES cohort.

Outcome Measures

Percentage of LBP reported.

Methods

LBP reported in the 1999-2004 miscellaneous pain NHANES questionnaire was the dependent variable examined. Covariates included HbA1c, BMI, age, and family income ratio to poverty as continuous variables as well as race, gender, and smoking as binary variables. Individuals were further subdivided by weight class and diabetes status. Regression and graphical analyses were performed on the study population as a whole and also on subpopulations.

Results

Increasing HbA1c did not increase the odds of reporting LBP in the full cohort. However, multivariate logistic regression of the 6 subpopulations revealed that the odds of LBP significantly increased with increasing HbA1c levels in normal weight diabetics. No other subpopulations reported significant relationships between LBP and HbA1c. LBP was also significantly associated with BMI for normal weight diabetics and also for obese subjects regardless of their DM status.

Conclusions

LBP is significantly related to DM status, but this relationship is complex and may interact with BMI. These results support the concept that LBP may be improved in normal weight diabetic subjects with improved glycemic control and weight loss, and that all obese LBP subjects may benefit from improved weight loss alone.  相似文献   
89.
Affinity peptide and protein‐ (APP) based radiotracers are an increasingly popular class of radiotracer in positron emission tomography (PET), which was once dominated by the use of small molecule radiotracers. Radiolabelled monoclonal antibodies (mAbs) are important examples of APPs, yet a preference for smaller APPs, which exhibit fast pharmacokinetics and permit rapid PET aided diagnosis, has become apparent. 18F exhibits favourable physical characteristics for APP radiolabelling and has been described as an ideal PET radionuclide. Notwithstanding, 18F radiolabelling of APP is challenging, and this is echoed in the literature where a number of diverse approaches have been adopted. This review seeks to assess and compare the approaches taken to 18F APP radiolabelling with the intention of highlighting trends within this expanding field. Generic themes have emerged in the literature, namely the use of mild radiolabelling conditions, a preference of site‐specific methodologies with an impetus for short, automated procedures which produce high‐yielding [18F]APPs.  相似文献   
90.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号